A gas that behaves as randomly moving, non-interacting molecules. This allows a simplified equation of state.

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2answers
32 views

Pressure exerted by a gas and the ideal gas equation

While determining the pressure exerted by any gas at a temperature why do we not consider the surface area of the container in which it is kept? We say that : P=nRT/V, where, n is the no. of moles, R ...
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1answer
29 views

Do air particles always rush to fill a container?

I'm sitting here in the metro station, drinking a bottle of water, and watching how the flow of water out of my mouth changes as air rushes into the bottle. My questions is: in space, obviously the ...
2
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4answers
493 views

Conversion of ideal gas to real gas via $Z$ compression factor

The ideal gas equation $PV=nRT$ can be converted into real gas equation by compression factor $Z$ i.e $PV=Z~ nRT)$. My question is what is $Z$ and how does it arise? Is $PV/nRT$ a compression ratio of ...
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1answer
17 views

Volume of Air pumped in Isothermal system [on hold]

A manual bicycle tire pump has a cylinder with volume V. When the piston is extended, the valve to the tire closes, and air at atmospheric pressure enters into the cylinder through another valve in ...
1
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1answer
316 views

Gas compressed and cooled

If a certain amount of a gas is compressed into a cylinder by the action of a piston that reduces its volume (lets say at a low speed), the kynetic energy of the gas molecules increases, what is ...
1
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0answers
25 views

How do I compute mass flow rate for a compressible fluid?

Consider the vacuum chamber in the figure. If a hole with cross section area $A_{cs}$ is created, how can I approximate the maximum mass flow rate, $\dot{m}$, for a compressible fluid (e.g. air)?
2
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0answers
24 views

Ratio of Stagnation to Normal Flow Properties in Incompressible Flows

I know in compressible flows the ratio of stagnation to normal flow variables is a function of the Mach number and usually the specific heat ratio. Does this ratio mean anything for incompressible ...
2
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3answers
37 views

Gas pressure within containers [on hold]

If, hypothetically, a gas had no inner pressure, and it was made to fill up a container. If, then, the pressure within the container was increased by filling it up with yet more gas, until high ...
0
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1answer
38 views

Why does stagnation pressure reduce across a normal shock?

I am seeking an explanation for this graph where the subscript "1" refers to the supersonic region and the subscript "2" refers to the subsonic region present beyond a normal shock. The static ...
0
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2answers
230 views

Viscosity for steam in the Reynolds number

In calculating the Reynolds number for a flow of steam in a pipe, this is the general formula I am trying to use: $$Re=\frac{\rho d v}{\mu}$$ with density $\rho$, pipe diameter $d$, flow steam $v$ ...
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2answers
35 views

estimating deviations from ideal gas behaviour

How can one estimate the pressure at which argon atoms show deviations from ideal gas behaviour due to the finite size of the atoms? I have tried Taylor expanding the hard sphere gas equation: ...
0
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1answer
31 views

Why do molecules in a gas not generally arrange themselves at the distance of minimum potential energy (Lennard-Jones 6-12 potential)

As the title suggests, why is this? Is it because the distance of molecules in a gas is too large (compared to in liquids/solids)? Or are there other reasons for this?
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1answer
123 views

Why is it not possible to use the ideal gas law to determine if the pressure changed in this situation?

I was given this question for my homework: A cylinder with a valve at the bottom is filled with an ideal gas. The vale is now opened and some of the gas escapes slowly. The valve is then closed, ...
0
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1answer
49 views

How does pressure change over time in an open box?

Imagine that you have a 1 cubic meter metal box with two 20 mm diameter holes. One of them is connected to an air-compressor that constantly pressurizes the inside of cube. Let's say 5 atm. The other ...
3
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1answer
42 views

Behavior of atom's wave packets in a gas

It is my understanding that the wave packet of a free localized particle spreads with time. My question is what is the best description of the particles in a gas inside a closed container: Do they ...
0
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0answers
13 views

Kinetic gas theory: How large are rotational and vibrational energy for a linear diatomic molecule?

Let's say one has given a temperature of a simple linear diatomic gas like Hydrogen $H_2$. From the temperature one knows the energy of the gas, but how does this energy "split up" to the different ...
6
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1answer
876 views

Why is it difficult to mix helium and nitrogen gases?

I recently learned an interesting fact: That it's difficult to mix helium and nitrogen gases in a compressed gas cylinder. Gas suppliers that need to mix the two gases have to rotate the cylinders for ...
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1answer
64 views

Deriving Ideal Gas law from Hamiltonian Mechanics

I just don't understand the explanation in Wikipedia. Is there a nice & elegant way of arriving at the Ideal Gas Law from Hamilton's Equations?
3
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8answers
256 views

Ideal gas law: Will the piston move at all?

We have the following experimental setup: Before the experiment starts: $$p_1=p_2; \space V_1=V_2; T_1=T_2+\Delta T$$ The experiment starts and both the containers are heated so that the ...
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2answers
64 views

Intuitive explanation of the shape of the Maxwell-Boltzmann distribution

At higher temperatures (for an ideal gas), the Maxwell-Boltzmann distribution is spread more widely and has a lower maximum. At lower temperatures, the spread is much more narrow and the peak is much ...
3
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2answers
69 views

Ideal gas equation and atmosphere of Venus

I'm teaching myself some basics of the ideal gas law and working out simple density equations for atmospheric gases at various altitudes. When I applied the gas law to Venus' atmosphere at its ...
2
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1answer
189 views

Bernoulli Equation for isentropic ideal gas flow

If one derives the Bernoulli Equation for the isentropic ideal gas flow you get: $$ \frac{1}{2}v^2 + g z + \left(\frac{\kappa}{\kappa -1} \right) \frac{p}{\rho} = const. $$ Two questions: Is ...
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2answers
44 views

Approximating Gas Density

So this was a random thought I had that I thought would be fun to mess around with using an Arduino and some sensors, but after the difficulty I've had I'm just curious to see if it can be done at ...
2
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2answers
13k views

Work Done in an Isobaric Process

I am given the information that an air parcel undergoes isobaric heating from 0° C to 20° C, and that's all I'm given. I have to determine the work done by the parcel on its surroundings. I know that ...
0
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2answers
36 views

Density of air using ideal gas law

I need to find the density of air using (I think) the ideal gas law. I have calculated $V$ of an ideal gas at s.t.p. to be $.0224m^3$. I am asked to find the density of air knowing it's temperature ...
0
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2answers
41 views

Does the increase of pressure of a gas also increase the energy?

It says that in adiabatic process, the heat is constant but the temperature is not. My question is, if you increase the pressure, the temperature is going to rise as pV = kT. But we know that the ...
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2answers
166 views

If I double the amount of oxygen molecules, do I double the paramagnetic force?

Oxygen is well known to be paramagnetic. If I take one molecule, $O_2$, and measure its paramagnetic force due to externally applied magnetic field, and then add another molecule near the first ...
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2answers
38 views

Mixture of different gases filling their container

If I have a closed container with a mixture of two or more gases $\rho_1$ and $\rho_2$ for instance at thermal equilibrium where $\rho_1>\rho_2$ how would I determine what percentage of the ...
0
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1answer
17 views

What are the assumptions made when analysing a stretched elastic string from a thermodynamic aspect?

Consider a stretched elastic string. Then conducting a thermodynamic analysis of the elastic string. The approach is very similar to that used for $(P, V, T)$ systems, with the pressure and volume ...
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3answers
240 views

Not Quasi-static, yet reversible process? Is this a valid example?

Imagine a gas (at room temp. and pressure) enclosed in a thermally insulating spherical container. At some instant, the container instantly expands symmetrically (radially outward) to, say, twenty ...
3
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1answer
36 views

Balloon of ideal gas suddenly pops in the vacuum of space - final average energy per atom?

My question is: is the following thinking pretty much correct? I'm interested hearing about anything here that is fundamentally wrong. Of course there is a bit of hand waving and approximation. If a ...
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1answer
42 views

Calculation of internal energy and entropy of ideal gas

I am having some trouble with calculation of entropy and internal energy for ideal gas. All sources which provide such derivations which I managed to find either assume a priori that $U$ is some ...
0
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2answers
36 views

Why does an ideal gas not consist of identical molecules? [closed]

since the mass , temperature , and number of particles are the same , shouldn't the molecules be the same so that the pressure of the gad is inversely proportional to the volume.
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0answers
20 views

If Earth's atmosphere would be cooled, how would its pressure change relative to its temperature?

I have a feeling it would not behave like an ideal gas? For example, if the atmosphere were to cool down at a constant 1 atm to 90 K, oxygen would liquefy. If changing of pressure would be ...
0
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2answers
95 views

Deriving the Ideal Gas Equation

Im specifically looking at how the IGE can be derived from the kinetic theory of gasses. Most textbooks and webpages I've viewed start off with a wall that the particle is hitting and then writes an ...
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2answers
132 views

physical meaning of pressure derivatives

Is there any physical meaning of the first and second derivatives of pressure with respect to time? If this helps, I am considering ideal gases.
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1answer
64 views

Pressure exerted by ideal gas on walls of container

All derivations I've come across are more or less similar to this: All of them take total momentum change as $2mv_{x}$ and divide it by total time to get the force exerted on the wall. That seems to ...
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0answers
22 views

Pressure in a balloon as a function of its diameter [duplicate]

Premise #1: Balloon is a perfect sphere Premise #2: We add water in order to increase the diameter of the balloon Is there an equation allowing us to find the pressure in the balloon, as the diameter ...
0
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1answer
66 views

What height is atmospheric pressure half that at sea level?

$PV = NT$, where T is a constant $P = \rho g h$ but I don't think this equation can hold in this form as the density is most definitely not constant as we go up in the atmosphere $\rho = ...
5
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2answers
7k views

Work done by isothermal expansion from two different viewpoints

Consider an adiabatic system as follows. It consists of a gas in a container and a piston. Initially, the system is at equilibrium and the gas inside it occupies a volume $V_i$ at a pressure $p_i$ ...
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0answers
49 views

Is it possible to consider PV diagrams without the equations of state?

Suppose that we have the equations of state for a particular system, or equivalently, that we have the fundamental relation $S = S(U,V,N)$. If we want to write down a PV diagram it will be quite ...
3
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2answers
110 views

Gases Expanding and Bonding in the Vacuum? Frozen Clouds

Why do gasses expand in space rather than attract forming a liquid? Do some gasses attract or bond when they get colder and what would be the characteristics of it in space? Would it be like powder ...
0
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1answer
51 views

The average value of the electric polarization of an ideal gas

An ideal gas consisting of $N$ molecules possessing an electric dipole moment $\mathbf{d}$, placed in a constant electric field intensity $\mathbf{E}$. Need to calculate the average of magnitude of ...
3
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2answers
173 views

How is the degenerate electron gas state “degenerate”?

What is "degenerate" in the degenerate electron gas state? Why is it called degenerate?
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0answers
26 views

What is meant by a “change in volume of a system”?

I keep getting confused when my professor talks about the change in volume of a system. Sometimes it seems as though he's talking about the volume of the gas and at other times he might be talking ...
1
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1answer
50 views

Free expansion of ideal gas, transient phase (3 questions)

We all know the classic scenario of free expansion. A contained gas expands into a vaccum and in the end we have $\Delta T = \Delta U = \Delta H = 0$ and $\Delta S = R \ln \frac{V_2}{V_1}$. This is ...
0
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5answers
52 views

How Heat is constant in adiabatic process

Consider adiabatic cylinder with a piston attached. $Q=0$ in this case and Work done is equal to change in internal energy. If I do work on the piston then its internal energy increases and so its ...
0
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1answer
63 views

Chemical Potential in the canonical and grand canonical ensemble

I'm studying the ideal Fermi gas from "Statistical Mechanics", by R. K. Pathria. In particular, the following formula, which can be found on page 237: \begin{equation} \mu=\left(\frac{3N}{4 \pi g ...
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2answers
19k views

Calculating work done on an ideal gas

I am trying to calculate the work done on an ideal gas in a piston set up where temperature is kept constant. I am given the volume, pressure and temperature. I know from Boyle's law that volume is ...